MichaelPage - 17:00, Wednesday 03 February 2021 (2363)
KAGRA QPD Linear range
Michael and Yuhang
After the measurement of the QPD spectrum with BS oplev in elog2532, we then measured the QPD linear range. We centered the beam on the QPD and checked the linear range while offsetting the beam position up, down, left and right.
When returning the beam position to "zero", the QPD reading didn't return to the zero value measured at the start of each run. So there is a bit of effect from suspended optics drift. This is why I split the data into 4 directions rather than just pitch and yaw.
Also, the QPD readings have a variation of about +/- 200 in pitch and ~+/- 300 in yaw.
After the measurement of the QPD spectrum with BS oplev in elog2532, we then measured the QPD linear range. We centered the beam on the QPD and checked the linear range while offsetting the beam position up, down, left and right.
When returning the beam position to "zero", the QPD reading didn't return to the zero value measured at the start of each run. So there is a bit of effect from suspended optics drift. This is why I split the data into 4 directions rather than just pitch and yaw.
Also, the QPD readings have a variation of about +/- 200 in pitch and ~+/- 300 in yaw.
Images attached to this report
